Apparatus and method for controlling time synchronization between base stations

Abstract

Provided are an apparatus and a method for controlling time synchronization between base stations when a receiving state of a satellite signal is poor. The present invention provide an apparatus and a method for controlling time synchronization between base stations that controls time synchronization between base stations based on reliability about time synchronization information of each base station.

1 . An apparatus for controlling time synchronization between base stations, the apparatus comprising:
 a time synchronization information collecting unit to collect, from each base station, time synchronization information for the time synchronization between the base stations;   a reliability determining unit to determine whether at least one reliability value among reliability values about a current time obtained from each time synchronization information is greater than a threshold; and   a time synchronization control unit to control the time synchronization between the base stations based on first time synchronization information associated with a reliability value greater than the threshold when at least one reliability value is greater than the threshold, and to control the time synchronization between the base stations based on predetermined second time synchronization information when all of the reliability values are less than the threshold.   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 a reliability determination control unit to control whether a reliability value obtained from a satellite signal for each base station is greater than the threshold to be determined; and   a current time information obtaining unit to obtain current time information from a first base station when there is the first base station of which the reliability value obtained from the satellite signal is greater than the threshold,   wherein the time synchronization control unit controls the synchronization based on the obtained current time information.   
     
     
         3 . The apparatus of  claim 1 , further comprising:
 a time synchronization information calculating unit to calculate third time synchronization information using a provided local oscillator for every predetermined time; and   a database constructing unit to construct a database to enable the first time synchronization information or the third time synchronization information to be available as the second time synchronization information for use of a backup.   
     
     
         4 . The apparatus of  claim 1 , further comprising:
 a base station state determining unit to primarily determine whether each base station receives a satellite signal for obtaining the time synchronization information, or to secondarily determine whether each base station is capable of calculating the reliability value, in interaction with the base stations; and   a drive control unit to control the time synchronization information collecting unit, the reliability determining unit, and the time synchronization control unit to be driven when at least one base station does not receive the satellite signal for obtaining the time synchronization information as a result of the primary determination, or when at least one base station does not calculate the reliability value as a result of the secondary determination.   
     
     
         5 . The apparatus of  claim 4 , wherein the base station state determining unit performs the primary determination or the secondary determination for every predetermined time. 
     
     
         6 . The apparatus of  claim 1 , further comprising:
 a reliability calculating unit to determine the reliability value for each base station using parameters that are obtained when processing a satellite signal for obtaining the time synchronization information.   
     
     
         7 . The apparatus of  claim 6 , wherein:
 the parameters include a signal to noise ratio (SNR) of the received satellite signal, a positioning error value by the received satellite signal, and pseudo distance information obtained from the received satellite signal, as elements, and   the reliability calculating unit determines the reliability value using at least one element.   
     
     
         8 . A method of controlling time synchronization between base stations, the method comprising:
 a time synchronization information collecting step of collecting, from each base station, time synchronization information for the time synchronization between the base stations;   a reliability determining step of determining whether at least one reliability value among reliability values about a current time obtained from each time synchronization information is greater than a threshold; and   a time synchronization control step of controlling the time synchronization between the base stations based on first time synchronization information associated with a reliability value greater than the threshold when at least one reliability value is greater than the threshold, and controlling the time synchronization between the base stations based on predetermined second time synchronization information when all of the reliability values are less than the threshold.   
     
     
         9 . The method of  claim 8 , further comprising:
 a reliability determination control step of controlling whether a reliability value obtained from a satellite signal for each base station is greater than the threshold to be determined; and   a current time information obtaining step of obtaining current time information from a first base station when there is the first base station of which the reliability value obtained from the satellite signal is greater than the threshold,   wherein the time synchronization control step controls the synchronization based on the obtained current time information.   
     
     
         10 . The method of  claim 8 , further comprising:
 a time synchronization information calculating step of calculating third time synchronization information using a provided local oscillator for every predetermined time; and   a database constructing step of constructing a database to enable the first time synchronization information or the third time synchronization information to be available as the second time synchronization information for use of a backup.   
     
     
         11 . The method of  claim 8 , further comprising:
 a base station state determining step of primarily determining whether each base station receives a satellite signal for obtaining the time synchronization information, or secondarily determining whether each base station is capable of calculating the reliability value, in interaction with the base stations; and   a drive control step of controlling the time synchronization information collecting step, the reliability determining step, and the time synchronization control step to be sequentially performed when at least one base station does not receive the satellite signal for obtaining the time synchronization information as a result of the primary determination, or when at least one base station does not calculate the reliability value as a result of the secondary determination.   
     
     
         12 . The method of  claim 11 , wherein the base station state determining step performs the primary determination or the secondary determination for every predetermined time. 
     
     
         13 . The method of  claim 8 , further comprising:
 a reliability deciding step of determining the reliability value for each base station using parameters that are obtained when processing a satellite signal for obtaining the time synchronization information.   
     
     
         14 . The method of  claim 13 , wherein:
 the parameters include an SNR of the received satellite signal, a positioning error value by the received satellite signal, and pseudo distance information obtained from the received satellite signal, as elements, and   the reliability deciding step determines the reliability value using at least one element.